White tongue most of the time, I'm curious if I have deficient immune system?

Workup and treatment. There is a condition called thrush which may result in a coated flaky white surface of the tongue. This is caused by a fungus and is treatable. Patients though who experience recurrent or difficult to treat fungal infections should consult their physicians regarding additional testing including a CD4, CD8 count, and total white cell count and differential.
See doctor. There are many causes for a white coating on the tongue. An ENT specialist can help you get to the bottom of the issue.